Starting work for focal point zooming.
Quick reference for myself
Remove _focalStart
Update demo and homepage for focal point zooming (for when it's working)
Merge branch 'master' into focal

* master:
  Add more demos. Also fixes an issue with contain: true. Close gh-23.
  FAQ link
  Add FAQ section to the README
  Release minor patch v1.4.2
  Do not pan during a pinch if disablePan is true. Supplements gh-21.
  Only call setMatrix once during a pinch gesture. Related to gh-21.
  Remove unnecessary var
  Build version number to README

Conflicts:
	README.md
	bower.json
	demo/index.html
	dist/jquery.panzoom.js
	dist/jquery.panzoom.min.js
	jquery.panzoom.js
	package.json
	panzoom.jquery.json
Fix demo
Add feature: focal-point zooming. Fixes gh-10.